Cryosurgical catheter

ABSTRACT

A cryogenic catheter includes an outer flexible member having at least one cryogenic fluid path through the flexible member. The at least one fluid path is defined by a plurality of flexible members disposed within the outer flexible member.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of application Ser.No. 08/893,825 filed Jul. 11, 1997, and titled “Cryosurgical LinearAblation Structure” which is a continuation-in-part of application Ser.No. 08/807,382, filed Feb. 27, 1997, and titled “Cryosurgical LinearAblation.”

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

FIELD OF THE INVENTION

[0003] The invention relates to catheters, and more particularly tocryosurgical catheters used for tissue ablation.

BACKGROUND OF THE INVENTION

[0004] Many medical procedures are performed using minimally invasivesurgical techniques, wherein one or more slender implements are insertedthrough one or more small incisions into a patient's body. With respectto ablation, the surgical implement can include a rigid or flexiblestructure having an ablation device at or near its distal end that isplaced adjacent to the tissue to be ablated. Radio frequency energy,microwave energy, laser energy, extreme heat, and extreme cold can beprovided by the ablation device to kill the tissue.

[0005] With respect to cardiac procedures, a cardiac arrhythmia can betreated through selective ablation of cardiac tissue to eliminate thesource of the arrhythmia. A popular minimally invasive procedure, radiofrequency (RF) catheter ablation, includes a preliminary step ofconventional electrocardiographic mapping followed by the creation ofone or more ablated regions (lesions) in the cardiac tissue using RFenergy. Multiple lesions are frequently required because theeffectiveness of each of the proposed lesion sites cannot bepredetermined due to limitations of conventional electrocardiographicmapping. Often, five lesions, and sometimes as many as twenty lesionsmay be required before a successful result is attained. Usually only oneof the lesions is actually effective; the other lesions result inunnecessarily destroyed cardiac tissue.

[0006] Deficiencies of radio frequency ablation devices and techniqueshave been overcome by using cold to do zero degree or ice mapping priorto creating lesions, as taught in U.S. Pat. Nos. 5,423,807; and5,281,213; and 5,281,215. However, even though combined cryogenicmapping and ablation devices permit greater certainty and less tissuedamage than RF devices and techniques, both the cryogenic and the RFdevices are configured for spot or roughly circular tissue ablation.

[0007] Spot tissue ablation is acceptable for certain procedures.However, other procedures can be more therapeutically effective ifmultiple spot lesions along a predetermined line, or a single elongateor linear lesion is created in a single ablative step. Radio frequencyablation devices are known to be able to create linear lesions bydragging the ablation tip along a line while it is active. However, nocryogenic devices are known that are optimized for, or which are evenminimally capable of, creating an elongate lesion.

SUMMARY OF THE INVENTION

[0008] The present invention provides a cryogenic catheter having anelongate outer member and a plurality of inner members disposed withinthe elongate outer member. The inner members have a plurality ofcontrollable openings formed thereon for the selective release ofcryogenic fluid. A plurality of electrode members are disposed on anexternal surface of the outer member. The inner members may bepositioned in a staggered configuration or alternatively at least oneinner member may be disposed within another inner member. In such aconfiguration, one of the inner members may be slidable or rotatable tothe other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] A more complete understanding of the present invention and theattendant advantages and features thereof will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

[0010]FIG. 1 is a schematic illustration of an embodiment of acryosurgical system in accordance with the invention;

[0011]FIG. 2 is a schematic depiction of the chambers of the heartshowing placement of the catheter of FIG. 1;

[0012]FIG. 3 illustrates the tip region of one embodiment of thecatheter in accordance with the invention;

[0013]FIG. 4 illustrates an alternative embodiment of the catheter ofFIG. 3;

[0014]FIG. 5 illustrates yet another embodiment of the catheter;

[0015]FIG. 6 illustrates a deformable tip for a catheter;

[0016]FIG. 7 illustrates yet another embodiment of the catheter;

[0017]FIG. 8 is a sectional view of the catheter of FIG. 7 taken alongline 8-8;

[0018]FIG. 9 is a sectional view of an alternative embodiment of thelinear ablation catheter illustrated in FIG. 7;

[0019]FIG. 10 illustrates an expansion chamber within a portion of ahelical coil;

[0020]FIG. 11 illustrates a portion of a catheter having an elongate,thermally-transmissive strip;

[0021]FIG. 12 is a sectional view of the catheter of FIG. 3 taken alongline 12-12;

[0022]FIG. 13 is a sectional view of the catheter of FIG. 3 taken alongline 13-13;

[0023] FIGS. 14-16 are sectional views of additional catheterembodiments;

[0024]FIG. 17 illustrates an inner face of a flexible catheter member;

[0025]FIG. 18 depicts yet another embodiment of a catheter in accordancewith the invention;

[0026]FIG. 19 is a table illustrating cooling performance of a catheterin accordance with the invention;

[0027]FIG. 20 is a sectional view of another catheter embodiment;

[0028]FIG. 21 is a sectional view of a portion of the catheter of FIG.20;

[0029]FIG. 22 is a detailed view of an area of the catheter portionillustrated in FIG. 21;

[0030]FIG. 23 is an illustration of yet another catheter embodiment;

[0031]FIG. 24 depicts still another catheter embodiment;

[0032]FIG. 25 illustrates yet another embodiment of the catheter;

[0033]FIG. 26 is a sectional view of the catheter of FIG. 25 taken alongline 26-26;

[0034]FIG. 27 illustrates yet still another embodiment of the catheter;

[0035]FIG. 28 illustrates the catheter of FIG. 27 in a secondconfiguration;

[0036]FIG. 29 is a sectional view of the catheter of FIG. 28 taken alongline 29-29;

[0037]FIG. 30 is a sectional view of the catheter of FIG. 28 taken alongline 30-30;

[0038]FIG. 31 illustrates yet another embodiment of the catheter;

[0039]FIG. 32 illustrates the catheter of FIG. 31 in a secondconfiguration;

[0040]FIG. 33 is a sectional view of the catheter of FIG. 32 taken alongline 33-33;

[0041]FIG. 34 is a sectional view of the catheter of FIG. 32 taken alongline 34-34;

[0042]FIG. 35 illustrates yet another embodiment of the catheter;

[0043]FIG. 36 is a sectional view of yet another embodiment of thecatheter;

[0044]FIG. 37 is a sectional view of the catheter of FIG. 36 afterrotation;

[0045]FIG. 38 illustrates yet another embodiment of the catheter; and

[0046]FIG. 39 illustrates the catheter of FIG. 38 in a secondconfiguration.

DETAILED DESCRIPTION OF THE INVENTION

[0047]FIG. 1 is a schematic illustration of a cryosurgical system inaccordance with the invention. The system includes a supply of cryogenicor cooling fluid 10 in communication with the proximal end 12 of aflexible catheter 14. A fluid controller 16 is interposed or in-linebetween the cryogenic fluid supply 10 and the catheter 14 for regulatingthe flow of cryogenic fluid into the catheter in response to acontroller command. Controller commands can include programmedinstructions, sensor signals, and manual user input. For example, thefluid controller 16 can be programmed or configured to increase anddecrease the pressure of the fluid by predetermined pressure incrementsover predetermined time intervals. In another exemplary embodiment, thefluid controller 16 can be responsive to input from a foot pedal 18 topermit flow of the cryogenic fluid into the catheter 14. One or moretemperature sensors 20 in electrical communication with the controller16 can be provided to regulate or terminate the flow of cryogenic fluidinto the catheter 14 when a predetermined temperature at a selectedpoint or points on or within the catheter is/are obtained. For example atemperature sensor can be placed at a point proximate the distal end 22of the catheter and other temperature sensors 20 can be placed at spacedintervals between the distal end of the catheter and another point thatis between the distal end and the proximal end.

[0048] The cryogenic fluid can be in a liquid or a gas state. Anextremely low temperature can be achieved within the catheter, and moreparticularly on the surface of the catheter by cooling the fluid to apredetermined temperature prior to its introduction into the catheter,by allowing a liquid state cryogenic fluid to boil or vaporize, or byallowing a gas state cryogenic fluid to expand. Exemplary liquidsinclude chlorodifluoromethane, polydimethylsiloxane, ethyl alcohol,HFC's such as AZ-20 (a 50-50 mixture of difluoromethane &pentafluoroethane sold by Allied Signal), and CFC's such as DuPont'sFreon. Exemplary gasses include nitrous oxide, and carbon dioxide.

[0049] The catheter 14 includes a flexible member 24 having athermally-transmissive region 26 and a fluid path through the flexiblemember to the thermally-transmissive region. A fluid path is alsoprovided from the thermally-transmissive region to a point external tothe catheter, such as the proximal end 12. Although described in greaterdetail below, exemplary fluid paths can be one or more channels definedby the flexible member 24, and/or by one or more additional flexiblemembers that are internal to the first flexible member 24. Also, eventhough many materials and structures can be thermally conductive orthermally transmissive if chilled to a very low temperature and/or coldsoaked, as used herein, a “thermally-transmissive region” is intended tobroadly encompass any structure or region of the catheter 14 thatreadily conducts heat.

[0050] For example, a metal structure exposed (directly or indirectly)to the cryogenic fluid path is considered a thermally-transmissiveregion 26 even if an adjacent polymeric or latex catheter portion alsopermits heat transfer, but to a much lesser extent than the metal. Thus,the thermally-transmissive region 26 can be viewed as a relative term tocompare the heat transfer characteristics of different catheter regionsor structures.

[0051] Furthermore, while the thermally-transmissive region 26 caninclude a single, continuous, and uninterrupted surface or structure, itcan also include multiple, discrete, thermally-transmissive structuresthat collectively define a thermally-transmissive region that iselongate or linear. Depending on the ability of the cryogenic system, orportions thereof, to handle given thermal loads, the ablation of anelongate tissue path can be performed in a single or multiple cycleprocess without having to relocate the catheter one or more times ordrag it across tissue. Additional details of the thermally-transmissiveregion 26 and the thermal transfer process are described in greaterdetail below.

[0052] In exemplary embodiments of the invention, thethermally-transmissive region 26 of the catheter 14 is deformable. Anexemplary deformation is from a linear configuration to an arcuateconfiguration and is accomplished using mechanical and/or electricaldevices known to those skilled in the art. For example, a wall portionof the flexible member 24 can include a metal braid to make the cathetertorqueable for overall catheter steering and placement. Additionally, acord, wire or cable can be incorporated with, or inserted into, thecatheter for deformation of the thermally transmissive region 26.

[0053] The cryogenic system of FIG. 1 is better understood withreference to its use in an operative procedure as shown in FIG. 2.Following the determination of a proposed lesion site within a heartchamber 28, for example, the catheter 14 is directed through a bloodvessel 30 to a region within the heart, such as an atrial or ventricularchamber, where the lesion will be made. The thermally-transmissiveregion 26 is placed proximate to the tissue to be ablated. Thethermally-transmissive region of the catheter may be deformed to conformto the curvature of the tissue before, during, or after placementagainst the tissue. The controller 16 allows or causes cryogenic fluidto flow from the cryogenic fluid supply 10 to the fluid path in thecatheter 14 and thence to the thermally-transmissive region 26 to ablatethe desired area or to cold map along the same tissue area. In oneembodiment (e.g., FIG. 12) a first conduit is concentric within a secondconduit and cooling fluid travels to a thermally-transmissive regionproximate a closed distal end of the catheter through a first conduit(fluid path) and is exhausted from the catheter through the secondconduit (fluid path).

[0054] Having described the function of the cryogenic catheter 14 andits use in a system context, several exemplary embodiments of thethermally-transmissive region 26 of the catheter are now described ingreater detail. FIGS. 3, 4, 5, 12-16 and 18 illustrate embodiments ofthe catheter, or portions thereof, having two or morethermally-transmissive segments in a spaced-apart relationship. Each ofthe illustrated catheters includes a closed tip 32 that can include athermally-transmissive material.

[0055] Referring specifically to the embodiment depicted in FIG. 3,multiple thermally-transmissive elements 34 are integral with a distalportion of a catheter. Each of the thermally-transmissive elements 34includes a first side or face 36 (shown in FIGS. 12 and 13) exposed to acryogenic fluid path and cryogenic fluid (shown by arrows) and a secondside or face 38 exposed to points exterior to the catheter. As shown inFIG. 13, the first side 36 and/or second side 38 of any or all of thethermally-transmissive elements 34 can be substantially flush with,recessed below, or protruding from the inner surface 40 and outersurface 42 of a portion of the catheter. The thermally-transmissiveelements 34 are separated by flexible portions of material 44 than canrange from slightly less thermally-transmissive than the adjacentthermally-transmissive elements to substantially lessthermally-transmissive than the adjacent elements. In the illustratedembodiment of FIG. 3, the thermally-transmissive elements 34 areannular, cylindrical elements which are made of gold-plated copper orbronze. Thermocouples 35 can be associated with one or more of theelements 34 and the tip 32. The thermally-transmissive elements 34 canbe completely exposed, embedded, or a combination thereof along the full360° of the catheter's circumference. In certain applications thethermally-transmissive elements traverse or define less than 360° of thecatheter's circumference as shown in FIGS. 14-16 and as described below.The longitudinal width of each thermally-transmissive element 34, thespacing between elements, the material thickness, and the materialcomposition are matched with a selected cryogenic fluid, one or morecryogenic fluid delivery locations within the catheter and fluiddelivery pressure to produce overlapping cold regions which produce alinear lesion.

[0056] The embodiment illustrated in FIG. 4 is substantially identicalto the embodiment of FIG. 3, however, at least one of thethermally-transmissive elements 34 includes a first open end 46 thatdefines a first plane and a second open end 48 that defines a secondplane, wherein the first and second planes intersect to give the annularelements a wedge-like appearance. Such a configuration permits adjacentthermally-transmissive elements 34 to be positioned very closelytogether, but it can limit the possibilities for deforming thethermally-transmissive region 26, which, in this embodiment, is flexiblein the direction indicated by the arrow.

[0057] With respect to the embodiments shown in both FIGS. 3 and 4, thethermally-transmissive elements 34 are substantially rigid and areseparated and/or joined by a flexible material 44. However, in otherembodiments the thermally-transmissive elements 34 are flexible and areinterdigitated with either rigid or flexible segments. FIG. 5, forexample, illustrates an embodiment of the cryogenic catheter havingthree thermally-transmissive elements 34 that are flexible. Theflexibility is provided by a folded or bellows-like structure 50. Inaddition to being shapable, a metal bellows can have enough stiffness toretain a selected shape after a deforming or bending step.

[0058] Instead of, or in addition to, flexible, thermally-transmissiveelements 34 and/or flexible material 44 between elements, the distal tip32 (or a portion thereof) can be deformable. For example, FIG. 6illustrates a tip 32 having thermally-transmissive, flexible, bellows50.

[0059] Referring now to FIGS. 7-10, a different approach is shown forproviding multiple thermally-transmissive segments in a spaced-apartrelationship. FIG. 7 illustrates a catheter embodiment having anelongate, thermally-transmissive region 26 that includes a helical coil52 at least partially embedded in the flexible member 24. As shown inFIG. 8, at least a first portion 54 of the helical coil 52 is exposed toa fluid path within the flexible member 24 and a second portion 56 ofthe helical coil is exposed to the exterior of the flexible member. Asdescribed above with respect to FIG. 13, the first portion 54 of thecoil can be substantially flush with, recessed below, or protruding froman inner surface 58 of the flexible member 24. Similarly, the secondportion 56 of the coil 52 can be substantially flush with, recessedbelow, or protruding from an outer surface 60 of the flexible member 24.

[0060] In the embodiment of FIG. 8, the second portion 56 of the coil 52is exposed along only a portion of the outer circumference of theflexible member 24 to define a longitudinally-elongate,thermally-transmissive region 26. This configuration can be provided byeccentrically mating the helical coil 52 to the catheter so that thelongitudinal axis of the coil and the longitudinal axis of the catheterare substantially parallel. The eccentric positioning of the coil 52provides excellent cooling performance because the surface areaavailable for thermal exchange between the first portion 54 of coil andthe cryogenic fluid is greater than the surface area available forthermal exchange between the second portion 56 of the coil and adjacenttissue where cooling power is delivered by each exposed coil portion toprovide a linear lesion.

[0061] Referring now to FIG. 9, an alternative embodiment is shownwherein a first portion 62 of the coil 52 is exposed around the entirecircumference of the flexible member 24, and a second portion 64 isexposed to a fluid path around the inner surface of the flexible member24. This is achieved by having the longitudinal axis of the helical coil52 co-axial with the longitudinal axis of the catheter.

[0062] In the embodiments illustrated in FIGS. 7-9, the coil 52 issolid. However, in other embodiments the coil can be an elongate,hollow, gas expansion chamber. For example, FIG. 10 illustrates aportion of a helical coil 52 that includes a passage that defines atleast a portion of a fluid path through a flexible member of thecatheter. The coil 52 defines a first fluid path diameter at a fluidentry point 66 and a second fluid path diameter that is greater than thefirst fluid path diameter at a gas expansion or boiling location 68. Gasescaping from a fluid exit point 70 can be exhausted through an opencentral region of the coil and/or another passage through the flexiblemember 24.

[0063]FIG. 11 illustrates an embodiment of the catheter wherein acontinuous, elongate, thermally-transmissive strip 72 is longitudinallyintegrated with a flexible member 24. The strip can include abellows-like structure. As described above with respect to otherembodiments, a first portion of the strip can be substantially flushwith, recessed below, or protrude from the outer surface of the flexiblemember. Similarly, a second portion of the strip can be substantiallyflush with, recessed below, or protrude from an inner surface of theflexible member.

[0064] Referring now to FIG. 12, an embodiment of the catheter isillustrated having a second or inner flexible member 74 within a lumenof first or outer flexible member 24, wherein the second flexible memberdefines a fluid path to the thermally-transmissive region 26. The innermember 74 can include a single opening 76 at or near the tip 32.Cryogenic fluid is expelled from the opening 76 and returns to theproximal end of the catheter along a fluid path defined by the outerwall of the inner member 74 and the inner wall of the outer member 24.This fluid path configuration is also partially illustrated in FIGS. 8,9, and 13. Alternatively, as also shown in FIG. 12, the inner member 74can be provided with multiple openings 78 proximate to and/or alignedwith the inner face of one or more thermally-transmissive elements 34 toachieve more uniform cooling across the entire elongate,thermally-transmissive region 26.

[0065] Referring now to FIGS. 14-16, sectional views of catheterembodiments are illustrated to show alternative configurations forthermally-transmissive elements. The previously describedthermally-transmissive elements 34 are arcuate and form complete andcontinuous 360 degree structures that traverse the completecircumference of the catheter, notwithstanding being flush with,depressed below, or raised above the outermost surface of the flexiblemember 24. However, the arcuate elements 34′, 34″, and 34′″ illustratedin FIGS. 14-16, respectively, traverse less than 360 degrees of thecircumference of the first flexible member and do not form completeloops. For example, in FIG. 14, element 34′ defines an approximately 270degree arc. In FIG. 15 the thermally-transmissive element 34″ defines anapproximately 180 degree arc; and in FIG. 16, the thermally-transmissiveelement 34′″ defines an approximately 90 degree arc. A catheter caninclude combinations of element types, such as a complete ring or loopelement, a 270 degree element and a 180 degree element as desired todefine a thermally transmissive region. In addition to the havingapplicability with respect to rigid thermally-transmissive elements, thebellows-like elements can also be less than 360 degrees.

[0066] The less than 360 degree arcuate elements provide uniquefunctional benefits with respect to thermal transfer and flexibility ofthe thermally-transmissive region. For example, because the portion ofthe catheter between the opposing ends of element 34′, 34″, 34′″ doesnot include a rigid structure, but rather only the resilient material offlexible member 24, the thermally-transmissive region of the cathetercan be more tightly curved (gap between ends inward and element facingoutward) than it could with complete 360 degree structures, especiallyif the elements are relatively long longitudinally.

[0067] The inner member 74 can be adapted to direct cooling fluid atonly the thermally transmissive element(s) and the shape and/or thenumber of openings for cooling fluid can be configured differentlydepending on the length of the arc defined by the thermally-transmissiveelement(s). For example, FIG. 14 illustrates an embodiment of the innermember having three openings opposing the thermally transmissive element34′; FIG. 15 illustrates two openings for a smaller arc; and FIG. 16discloses a single opening for an even smaller arc.

[0068] Another advantage to providing one or more thermally-transmissiveelements that have a less than 360 degree configuration is that limitingthe span of the elements to a desired lesion width, or somewhat greaterthan a desired lesion width, reduces the thermal load on the systemand/or permits colder temperatures to be achieved than with respect to acomplete 360 degree structure. Unnecessary and perhaps undesirablecooling does not occur at any other location along the catheter exceptat an elongate region of predetermined width. A similar effect can alsobe achieved by providing a non-circular 360 degree element or byeccentrically mounting a circular 360 degree element with respect to theflexible member, wherein a portion of the 360 degree element is embeddedwithin the wall of the flexible member or otherwise insulated from thecryogenic fluid path in a manner similar to that shown in FIG. 8.

[0069] Referring now to FIG. 17, a portion of the inner face of an outerflexible member showing in an exemplary embodiment, thermal transferpins 80 protruding from the inner face of a thermally-transmissiveelement 34. The pins permit thermal transfer through the flexible member24. As with the other features of the invention, the pins are equallysuitable for complete 360 degree element structures or less than 360degree structures. Although only pins are shown on any geometric orsurface means to increase heat transfer including but not limited topins, irregularities, channels or surface modifications may be used.

[0070] Referring now to FIG. 18, yet another embodiment of the catheteris shown wherein rigid metal rings 34 a-c are interdigitated withflexible segments 44 a-c to define a first flexible member and athermally-transmissive region approximately one inch in length. A secondflexible member is concentric within the first flexible member and hasan outlet for cryogenic fluid at its distal end. Thermocouples 82 a-ccan be associated with one or more of the rings 34 a-c.

[0071] It has been described above how the thermal loading of a coolingsystem can be reduced by providing thermally-transmissive elements thatspan less than 360 degrees. However, the thermal loading can also bereduced by sequentially cooling the thermally-transmissive region. Oneway to sequentially cool is to modulate the pressure of the coolingfluid along the fluid path through the flexible member. This modulationcan be performed by the fluid controller which can be programmed toincrease and decrease the pressure of the fluid by predeterminedpressure increments over predetermined time intervals. When thecryogenic fluid is a liquid that provides cooling by changing phase fromliquid to gas, the change of pressure alters the physical location alongthe fluid path where the phase change takes place and concomitantlychanges the point of coldest temperature along thethermally-transmissive region. Thus, varying the pressure of the fluidcan provide a moving ice-formation “front” along the catheter, enablingthe creation of a linear lesion.

[0072] Therefore, a method of forming an elongate tissue lesion caninclude the following steps using any of the above described cathetershaving an elongate, thermally-transmissive region. In a first step acryogenic fluid is introduced into the flexible member at a firstpredetermined pressure. Next, the pressure of the cryogenic fluid isincrementally increased within the flexible member until a secondpredetermined pressure is achieved. Similarly, the pressure of thecryogenic fluid within the flexible member can be decreasedincrementally from the second predetermined pressure to the firstpredetermined pressure, wherein the steps of incrementally increasingand decreasing the pressure define a thermal cycle. Typically, from oneto eight thermal cycles are required to achieve a desired therapeuticeffect. In an exemplary method, about ten increments of about fiveseconds in duration are selected and pressure is increased by about 20to 40 pounds per square inch in each increment. Thus, using this methodan elongate lesion can be created in less than 20 minutes.

[0073]FIG. 19 is a table that illustrates sequential cooling in acatheter as described above having a thermally-transmissive region thatincludes a tip and three elements or rings. The table illustrates threetests conducted in a still bath at 37° C., using AZ-20 as the cryogenicfluid. Associated with each pressure increment are measured temperaturesat the tip, first ring, second ring, and third ring. The shaded regionillustrates the sequential movement of a target temperature range (upper−40's to low −50's) in response to a change in pressure. Although valuesare only provided for three rings, a similar effect and pattern isobtained with more than three rings or elements.

[0074] Turning now to FIG. 20, a thermally-transmissive portion ofanother embodiment of a medical device or structure such as a catheteris illustrated in a sectional view. The structure can include an innerpassage or lumen as described above with respect to other embodiments,but which is not shown in this illustration for purposes of clarity.Thus, the illustrated portion is the outer passage or lumen that definesan elongate ablation region. Thermally-transmissive elements 84, such asgold plated copper, are joined to adjacent elements by resilientconnecting elements 86, such as a stainless steel springs welded to theends of the elements 84. A resilient bio-compatible material 88 coversthe connecting elements 86 and the interstices between adjacentthermally-transmissive elements. In an exemplary embodiment, thematerial 88 is vulcanized silicone. It should be noted in theillustration that the surface of the elements 84 is contiguous andco-planar with the material 88 to provide a smooth outer surface.

[0075]FIG. 21 illustrates a single thermally-transmissive element 84having reduced diameter ends 90 and 92. The wider central portion 94provides an expansion chamber for gas (shown by arrows) exiting anapertured inner passage 96. FIG. 22 shows additional detail of the end90 of the element 84. The end 90 is textured, such as by providingserrations 98, to provide a good adhesion surface for the material 88.

[0076] Referring now to FIG. 23, a thermally-transmissive portion of yetanother embodiment of a flexible cryogenic structure is illustrated in asectional view. In this embodiment an inner, apertured structure 100 hasa flat wire 102 wrapped around it in a spiral manner.Thermally-transmissive segments 104 are disposed upon the wire 102 in aspaced-apart relationship, and a flexible, bio-compatible material 106fills the interstices between segments 104. A thermocouple 108 can beassociated with each segment 104. A wire 109 connects the thermocouple108 to instrumentation near the proximal end of the structure. Theexterior surface of the structure is smooth, and the structure caninclude 3 to 12 segments 104. In an exemplary embodiment the innerstructure 100 is made of PTFE, the material 106 is 33 D Pebax, and thewire 102 is stainless steel or Nitinol. An apertured inner passage(similar to that shown in FIG. 21) is placed within the structure.

[0077]FIG. 24 illustrates still another embodiment of a cryogeniccooling structure that includes a surface or wall 110 including apolymer or elastomer that is thin enough to permit thermal transfer. Forexample, polyamide, PET, or PTFE having a thickness of a typicalangioplasty balloon or less (below 0.006 inches) provides acceptablethermal transfer. However, the thinness of the wall 110 allows it toreadily collapse or otherwise deform under vacuum or near vacuumconditions applied to evacuate fluid/gas from the structure.Accordingly, the structure is provided with one or more supportingelements 112 such as a spring. The cooling structure is illustrated inassociation with a catheter 114 having a closed distal tip 116 and monoor bipolar ECG rings 118, 120, 122. The thermally-transmissive region isapproximately 30 mm in length and is effective for thermal transfer overits entire circumference. However, as illustrated in FIG. 11, thethermally-transmissive region can be confined to specific region(s) ofthe device's circumference.

[0078] Referring now to FIG. 25, an embodiment of the catheter isillustrated having three flexible members or injection tubes 210, 211and 212 disposed within a first or outer flexible member 200. In anexemplary embodiment, the inner flexible members 210, 211 and 212 arearranged in a staggered configuration within the outer flexible member200. As used herein, term “staggered” may be used to designate both alinearly/axially staggered configuration or alternatively, arotationally staggered configuration. The flexible members 210, 211 and212 thus define multiple staggered fluid paths within the outer member200. In such a configuration, the injection tubes 210, 211 and 212 allowfor greater aggregate cooling power as well as the creation of a varietyof different cooling/freeze zones 201, 203 and 205 along the length ofthe outer flexible member 200. In an exemplary embodiment, thermocouples204 disposed along the outer surface of the outer flexible member 200may be integrated with an internal feedback loop to provide independentand variable regulation of these freeze zones.

[0079] In an exemplary embodiment, the first inner member 210 includesat least one opening 214 positioned proximate an electrode ring member207. Cryogenic fluid is expelled from the opening 214 and returns to theproximal end of the catheter along a fluid path defined by the innerwall 218 of the outer member 200, as shown in FIG. 26. Similarly, thesecond inner member 211 includes at least one opening 215 positionedproximate a second electrode ring member 208. Cryogenic fluid is alsoexpelled from the opening 215 and returns to the proximal end of thecatheter along the fluid path defined by the inner wall 218 of the outermember 200. Similarly, the third inner member 212 includes at least oneopening 216 positioned proximate a third electrode ring member 209.

[0080] Alternatively, the catheter can be provided with only two innermembers, or four or more inner members, not shown, disposed within theouter member. The inner members would have one or more openingsproximate to and/or aligned with the inner face of one or moretransmissive elements, as described earlier herein, to achieve differentregions of freeze zones across the entire elongate member.Alternatively, all the staggered inner members may be simultaneouslyprovided with cryogenic fluid to create a linear lesion for selectedapplications. The flow of cooling fluid along the fluid paths throughthe flexible members can also be alternated in any number of patternsamong the multiple inner members to provide a desired cooling patternsuch as a discontinuous or a continuous lesion across the entirecatheter.

[0081] In an exemplary embodiment, a catheter with a plurality ofthermally conductive electrode rings would have an underlying injectiontube or tubes controlling the release of cryogenic fluid to eachelectrode. Such a catheter could be placed in the coronary sinus orendocardially along the atrioventricular junction. Once positioned, anelectrogram of interest is located using a specific electrode ring onthe catheter. Coldmapping may be performed on the selected location toconfirm the correctness of the location. Once, confirmed, the area iscryoablated using the same electrode ring. The same embodiments andothers described herein are equally suited to other organs besides theheart and/or any body portion that would benefit from the application ofthermal energy.

[0082] Referring now to FIG. 27, an embodiment of the catheter isillustrated having an outer member 220 with a fixed injection tube 230disposed within a slidable sheath or overtube 240 therein. The injectiontube and overtube are shown spaced apart for illustrative purposes only.Preferably, the injection tube is sized so that an outer surface of theinjection tube engages an inner surface of the overtube while stillallowing one member to slide or rotate relative to the other.

[0083] The fixed injection tube 230 has multiple openings 232, 234formed thereon and the slidable overtube also has multiple openings orports 242, 244 formed thereon. In one configuration shown in FIG. 27,opening 232 on the injection tube 230 coincides or is aligned withopening 242 on the slidable overtube 240. Thus, any fluid exiting theinjection tube 230 from opening 232 is able to escape through opening242.

[0084] As the slidable overtube 240 is slid or moved in a firstdirection as shown by arrow 236 along longitudinal axis 222, opening 232is covered or blocked by the surface of overtube 240 as now shown inFIG. 28. In a second configuration shown in FIG. 29, opening 234 ofinjection tube 230 is aligned with opening 244 of overtube 240. In thesame configuration, as shown in FIG. 30, opening 242 is not aligned withany opening formed on the surface of injection tube 230. Although onlyshown in two positions or configurations, the slidable overtube ispositionable in any number of positions relative to the fixed injectiontube. The overtube may also be used to partially-cover the openings onthe injection tube to provide for a limited or controlled flow ofcryogenic fluid.

[0085] Depending on which opening of the injection tube is aligned withthe openings formed on the overtube, cryogenic fluid is expelled fromthe opening and returns to the proximal end of the catheter along afluid path defined by the inner wall 226 of the outer member 220. Thenon-aligned opening will not expel fluid since the opening will beblocked. Alternatively, the injection tube and overtube can be providedwith three or more openings to achieve multiple cooling/freeze zonesalong the length of the catheter.

[0086] Referring now to FIG. 31, an embodiment of the catheter isillustrated having a slidable injection tube 260 disposed within a fixedsheath or overtube 270. As shown in FIG. 31, both the injection tube 260and overtube 270 are disposed within a flexible outer member 250. Theslidable injection tube 260 has multiple openings 262, 264 formedthereon which allows for the release of cryogenic fluid. The fixedovertube 270 also has multiple perforations or openings 272, 274 formedthereon which allows for the differential release of fluid as describedin more detail below. The injection tube may be further provided with athermistor 254 disposed proximate the distal end of the tube to providethermistor feedback. In one embodiment, the openings can be controlledby miniaturized means such as micro or nanovalves.

[0087] In a first configuration shown in FIG. 31, opening 262 of theinjection tube 260 coincides or is aligned with opening 274 of the fixedovertube 270. As the slidable injection tube 260 is slid or moved in afirst direction as shown by arrow 266, opening 262 is then aligned withcorresponding opening 272 on the overtube 270 in FIG. 32.

[0088] In this second configuration, as shown in FIGS. 32-34, openings262, 264 of injection tube 260 are aligned with openings 272, 274 ofovertube 270. Although only two configurations for the catheter areshown, the injection tube 260 is positionable in any number of locationsrelative to the fixed overtube 270.

[0089] In operation, cryogenic fluid is expelled from the openings andreturns to the proximal end of the catheter along a fluid path definedby an inner wall 256 of the outer member 250. Alternatively, theinjection tube 260 and overtube 270 can be provided with multipleopenings proximate to and/or aligned with the inner face of one or morethermally-transmissive elements as described earlier herein to achievemore uniform cooling across the entire elongate, thermally-transmissiveregion.

[0090] Referring to FIG. 35, an embodiment of the catheter isillustrated having an outer member 280 with an injection tube 290 withmultiple opposed openings 292-297 formed therein. Either the injectiontube 290 or the overtube 300 may be slidable in a longitudinal plane toexpose and/or cover one or more of the opposed openings on the injectiontube 290. For example, as shown in FIG. 35, openings 294, 295 formed onthe injection tube 290 are aligned with openings 302, 303 formed on theovertube 230. Furthermore, the injection tube may be positioned in aforwardmost position, not shown, to expose openings on the injectiontube proximate the tip of the catheter. In this configuration, theinjection tube would provide fluid to cool the area around the tip ofthe catheter.

[0091] In the embodiments described and shown above in FIGS. 32-35,electrode rings as shown in FIG. 25 may be provided along the outersurface of any of the outer members. The electrodes would serve both aselectrical conductors and as a thermal transmitter at each location.

[0092] Referring to FIGS. 36 and 37, an embodiment of the catheter isillustrated have one or more rotatable members disposed within aflexible outer member 310. In this embodiment, the catheter includes anovertube member 312 and an injection tube member 314, one or both ofwhich are rotatable with respect to one another. In an exemplaryembodiment as shown in FIGS. 36 and 37, the injection tube 314 isrotatable relative to the fixed overtube 312. The injection tube 314 maybe rotatable in either or both a clockwise and counterclockwisedirection as indicated by arrows 320 and 322. As shown in FIG. 36, in afirst configuration, opening 316 formed on the overtube 312 aligns withan opening 318 formed on the injection tube 314. As the injection tube314 is rotated in a counterclockwise direction, the opening 318 on theinjection tube 314 is placed out of alignment with the opening 316formed on overtube 312, as shown in FIG. 37. Alternatively, theinjection tube 314 may be fixed in the catheter while the overtube 312is rotatable. In another embodiment, both the injection tube andovertube may both be rotatable. In yet a further embodiment, theinjection tube and/or the overtube are rotatable and slidable within theouter member.

[0093] In the embodiments shown and described above, the slidable androtatable inner and outer tubes may have openings so arranged as toallow the fluid releasing openings to be in a variety of open and closedconfigurations with a minimum of relational movement between the tubes.For example, as shown in FIG. 38, an outer member 330 has disposedtherein one slidably disposed inner tube 336 which has openings 338formed thereon in a constant sequence, and a matching slidably disposedouter tube 332 which has openings 334 formed thereon in a constantsequence of slightly different length or intervals. In thisconfiguration, as shown in FIG. 39, small linear relational movementsbring the openings on the outer tube 332 and the inner tube 336 into anoverlapping configuration.

[0094] In addition, the openings as shown and described herein may be soshaped as to allow additional control of fluid release. For example, anouter hole could be tear-shaped and match up with an inner opening thatis tear-shaped rotationally aligned 180° oppositely not shown. As thetwo narrow ends begin to overlap with slidable motion, a tiny apertureis created. With further slidable motion in the same direction, largerareas of the two openings overlap and larger volumes of cryogenic fluidcan be released.

[0095] A variety of modifications and variations of the presentinvention are possible in light of the above teachings. Specifically,although many embodiments are illustrated being slender and flexible,other embodiments may be thick and rigid, and introduced into the bodydirectly through incisions or through structures such as trocars. Theopening and closing of the catheter openings may also be controlled byusing nanotechnology and miniaturized valving. Furthermore, althoughsome of the illustrated devices are particularly well suited for cardiacprocedures, the same embodiments and others are equally suited to otherorgans and/or any body portion that would benefit from the applicationof thermal energy. For example, the illustrated devices may be used fortreating arteries for restenosis or portions of the GI tract to stopbleeding or portions of the GU tract to treat spasm, inflammation,obstruction or malignancy. Thus, the devices as shown are not to belimited to catheters but should be viewed more broadly as cryogenicstructures or portions thereof. It is therefore understood that, withinthe scope of the appended claims, the present invention may be practicedotherwise than as specifically described hereinabove. All referencescited herein are expressly incorporated by reference in their entirety.

What is claimed is:
 1. A cryogenic catheter comprising: an elongateouter member; and a plurality of inner members disposed within theelongate outer member, the inner members defining at least one cryogenicfluid path through the outer member.
 2. The cryogenic catheter of claim1 , wherein at least one of the plurality of inner members has at leastone controllable opening formed thereon to selectively release cryogenicfluid.
 3. The cryogenic catheter of claim 2 , wherein the inner membershave a plurality of controllable openings positioned in a staggeredconfiguration.
 4. The cryogenic catheter of claim 2 , wherein theplurality of inner members includes an overtube and an injection tubeslidably disposed to one another.
 5. The cryogenic catheter of claim 4 ,wherein in one configuration at least one opening formed on the overtubealigns with at least one opening on the injection tube.
 6. The cryogeniccatheter of claim 2 , wherein the plurality of inner members includes anovertube and an injection tube which are rotatable with respect to oneanother.
 7. The cryogenic catheter of claim 6 , wherein in oneconfiguration at least one opening on the overtube aligns with at leastone opening on the injection tube.
 8. The cryogenic catheter of claim 2, wherein at least one of the plurality of openings is controlled by avalve.
 9. The cryogenic catheter of claim 8 , wherein the valve is aminiaturized mechanical valve.
 10. The cryogenic catheter of claim 1 ,wherein at least one of the plurality of the inner members has at leastone controllable opening formed thereon, each opening positionedproximate at least one electrode ring disposed on an outer surface ofthe elongate outer member.
 11. The cryogenic catheter of claim 10 ,wherein at least one opening releases cryogenic fluid so as to alter thetemperature of a region proximate to the electrode ring.
 12. Thecryogenic catheter of claim 10 , wherein the openings are selectivelyand independently controllable so as to alter the temperature of aregion proximate the electrode ring.
 13. The cryogenic catheter of claim10 , wherein the catheter allows the creation of at least one continuouslinear cryolesion.
 14. The cryogenic catheter of claim 10 , wherein thecatheter allows the creation of a single localized cryolesion.
 15. Thecryogenic catheter of claim 10 , wherein the catheter allows thecreation of at least two distinct cryolesions.
 16. The cryogeniccatheter of claim 1 , further comprising an array of controllableopenings adapted to release cryogenic fluid within the elongate outermember for deployment along a length of the outer member.
 17. Thecryogenic catheter of claim 16 , wherein at least one opening releasescryogenic fluid to create a single lesion.
 18. The cryogenic catheter ofclaim 16 , wherein a plurality of openings release cryogenic fluidsimultaneously to create a plurality of discontinuous lesions.
 19. Thecryogenic catheter of claim 18 , wherein a plurality of openings releasecryogenic fluid simultaneously to create a single continuous linearlesion.
 20. The cryogenic catheter of claim 16 , wherein a plurality ofopenings release cryogenic fluid at different times to create aplurality of discontinuous lesions.
 21. The cryogenic catheter of claim20 , wherein a plurality of openings release cryogenic fluid atdifferent times to create a single continuous linear lesion.
 22. Thecryogenic catheter of claim 1 , wherein a plurality of openings releasecryogenic fluid to increase the thermal power of the device.
 23. Acryogenic catheter comprising: an elongate outer member; a plurality ofinner members disposed within the elongate outer member, the innermembers having a plurality of controllable openings formed thereon forthe selective release of cryogenic fluid; and a plurality of electrodemembers disposed on an external surface of the outer member, at leastone electrode member positioned proximate at least one controllableopening.